fix: revert ExecutionContext reporting. (#3058)

It turned out that almost any usecase requires helper methods to access
DOM inside the ExecutionContext.

Instead of exposing execution contexts as-is, we should introduce
IsolatedWorld as a first-class citizen that will hold execution contexts
inside.

lib/ExecutionContext.js

@@ -31,24 +31,9 @@ class ExecutionContext {
     this._frame = frame;
     this._contextId = contextPayload.id;
     this._isDefault = contextPayload.auxData ? !!contextPayload.auxData['isDefault'] : false;
-    this._name = contextPayload.name;
     this._objectHandleFactory = objectHandleFactory;
   }
 
-  /**
-   * @return {string}
-   */
-  name() {
-    return this._name;
-  }
-
-  /**
-   * @return {boolean}
-   */
-  isDefault() {
-    return this._isDefault;
-  }
-
   /**
    * @return {?Puppeteer.Frame}
    */

lib/FrameManager.js

@@ -188,7 +188,6 @@ class FrameManager extends EventEmitter {
     this._contextIdToContext.set(contextPayload.id, context);
     if (frame)
       frame._addExecutionContext(context);
-    this.emit(FrameManager.Events.ExecutionContextCreated, context);
   }
 
   /**
@@ -201,18 +200,14 @@ class FrameManager extends EventEmitter {
     this._contextIdToContext.delete(executionContextId);
     if (context.frame())
       context.frame()._removeExecutionContext(context);
-    this.emit(FrameManager.Events.ExecutionContextDestroyed, context);
   }
 
   _onExecutionContextsCleared() {
-    const contexts = Array.from(this._contextIdToContext.values());
-    this._contextIdToContext.clear();
-    for (const context of contexts) {
+    for (const context of this._contextIdToContext.values()) {
       if (context.frame())
         context.frame()._removeExecutionContext(context);
     }
-    for (const context of contexts)
-      this.emit(FrameManager.Events.ExecutionContextDestroyed, context);
+    this._contextIdToContext.clear();
   }
 
   /**
@@ -281,8 +276,6 @@ class Frame {
     this._contextResolveCallback = null;
     this._setDefaultContext(null);
 
-    this._executionContexts = new Set();
-
     /** @type {!Set<!WaitTask>} */
     this._waitTasks = new Set();
     this._loaderId = '';
@@ -299,8 +292,7 @@ class Frame {
    * @param {!ExecutionContext} context
    */
   _addExecutionContext(context) {
-    this._executionContexts.add(context);
-    if (context.isDefault())
+    if (context._isDefault)
       this._setDefaultContext(context);
   }
 
@@ -308,8 +300,7 @@ class Frame {
    * @param {!ExecutionContext} context
    */
   _removeExecutionContext(context) {
-    this._executionContexts.delete(context);
-    if (context.isDefault())
+    if (context._isDefault)
       this._setDefaultContext(null);
   }
 
@@ -337,13 +328,6 @@ class Frame {
     return this._contextPromise;
   }
 
-  /**
-   * @return {!Array<!ExecutionContext>}
-   */
-  executionContexts() {
-    return Array.from(this._executionContexts);
-  }
-
   /**
    * @param {function()|string} pageFunction
    * @param {!Array<*>} args

lib/Page.js

@@ -121,8 +121,6 @@ class Page extends EventEmitter {
     this._frameManager.on(FrameManager.Events.FrameAttached, event => this.emit(Page.Events.FrameAttached, event));
     this._frameManager.on(FrameManager.Events.FrameDetached, event => this.emit(Page.Events.FrameDetached, event));
     this._frameManager.on(FrameManager.Events.FrameNavigated, event => this.emit(Page.Events.FrameNavigated, event));
-    this._frameManager.on(FrameManager.Events.ExecutionContextCreated, event => this.emit(Page.Events.ExecutionContextCreated, event));
-    this._frameManager.on(FrameManager.Events.ExecutionContextDestroyed, event => this.emit(Page.Events.ExecutionContextDestroyed, event));
 
     this._networkManager.on(NetworkManager.Events.Request, event => this.emit(Page.Events.Request, event));
     this._networkManager.on(NetworkManager.Events.Response, event => this.emit(Page.Events.Response, event));
@@ -1130,8 +1128,6 @@ Page.Events = {
   Metrics: 'metrics',
   WorkerCreated: 'workercreated',
   WorkerDestroyed: 'workerdestroyed',
-  ExecutionContextCreated: 'executioncontextcreated',
-  ExecutionContextDestroyed: 'executioncontextdestroyed',
 };